to use
3-1/2-inch tiles, or any larger size, much more care must be given to the
closing of the joints. All tiles, in manufacture, dry more rapidly at the
top, which is more exposed to the air, than at the bottom, and they are,
therefore, contracted and made shorter at the top. This difference is most
apparent in the larger sizes. The large _round_ tiles, which can be laid
on any side, can easily be made to form a close joint, and they should be
secured in their proper position by stones or lumps of earth, wedged in
between them and the sides of the ditch. The sole tiles must lie with the
shortest sides up, and, usually, the space between two tiles, at the top,
will be from one-quarter to one-half of an inch. To remedy this defect,
and form a joint which may he protected against the entrance of earth, the
bottom should he trimmed off, so as to allow the tops to come closer
together. Any opening, of less than a quarter of an inch, can he
satisfactorily covered,--more than that should not be allowed. In turning
corners, or in passing around curves, with large tiles, their ends must he
beveled off with the pick, so as to fit nicely in this position.

The best covering for the joints of tiles which are laid without collars,
is a scrap of tin, bent so as to fit their shape,--scraps of leather, or
bits of strong wood shavings, answer a very good purpose, though both of
these latter require to be held in place by putting a little earth over
their ends as soon as laid on the tile. _Very small_ grass ropes drawn
over the joints, (the ends being held down with stones or earth,) form a
satisfactory covering, but care should be taken that they be not too
thick. A small handful of wood shavings, thrown over the joints, also
answers a good purpose. Care, however, should always be taken, in using
any material which will decay readily, to have no more than is necessary
to keep the earth out, lest, in its decay, it furnish material to be
carried into the tile and obstruct the flow. This precaution becomes less
necessary in the case of drains which always carry considerable streams of
water, but if they are at times sluggish in their flow, too much care
cannot be given to keep them free of all possible causes of obstruction.
As nothing is gained by increasing the quantity of loose covering beyond
what is needed to close the joints, and as such covering is only procured
with some trouble, there is no reason for its extravagant use.

There